1. Field of the Invention
The invention relates to a toy car with adjustable magnetic adhesion for a racetrack.
2. The Prior Art
Toy cars of this type are driven by an electric motor, which draws its supply current via sliding brushes, which are in contact with current conductors of the roadbed. These current conductors are usually ferromagnetic and, via a permanent magnet in the toy car, increase the adhesion thereof to the roadbed during running.
German Patent 3327667 discloses a toy car with magnetic adhesion for an auto racetrack. This car contains vertically adjustable permanent magnets, in which the clearance between the permanent magnets and current conductors is adjustable with spacer plates. The holders of the permanent magnets and of the spacer plates are fastened with screws, which also connect the undercarriage and body.
Because of the need to use spacer plates, adjusting the clearance between the permanent magnet and current conductor is a complex process. Thus, it cannot be accomplished during normal operation of the toy.
German Patent 3240712 C2 describes a toy car with magnetic adhesion for an auto racetrack, in which the permanent magnet is disposed in a magnet holder mounted adjustably on the undercarriage. The height of the gap between the permanent magnet and current conductors can be adjusted. For this purpose, the magnet holder can also be disposed on an inclined plane, which is adjustable on a correspondingly inclined plane in the undercarriage. Adjustment is accomplished by a slide, which is provided with collapsible hook attachments, which are braced against a toothed rod disposed on the undercarriage. The magnet holder can also be mounted in a shaft disposed on the undercarriage and can be provided with an inclined guide groove, which slides on an inclined guide tongue.
The arrangement in which a magnet holder is used for holding and shifting the permanent magnet is technically complex, susceptible to malfunctions and associated with high costs.
It is therefore an object of the invention to provide a toy car with adjustable magnetic adhesion for an auto racetrack, which is of simpler design than in the prior art but nevertheless offers infinitely variable adjustment capability, is inexpensive to produce and is not susceptible to malfunctions.
In the toy car according to the invention, the permanent magnet can be shifted along guide rails of the chassis oriented at an incline relative to the roadbed plane. The guide rails are formed along the sides in a retaining means made in one piece with the chassis. The inside of the retaining means on the side of the permanent magnet opposite the roadbed contains a ferromagnetic adhesion plate disposed parallel to the guide rails, along which plate the permanent magnet can be shifted infinitely variably.
The permanent magnet""s retaining means, which has a substantially rectangular cross section, can be made in one piece with the bottom plate, so that no additional structural part is necessary. Because the permanent magnet adheres to a metal adhesion plate, it can be pushed thereon into any desired position, while at the same time no additional holding device is necessary to lock a shift position.
Preferably, the retaining means is located in the chassis between drive motor and front axle. Thus, the permanent magnet is located substantially at the center of gravity of the toy car, in which case the running characteristic and simultaneously the contact pressure can be varied by shifting the permanent magnet. Preferably, the inclined plane of the adhesion plate on which the permanent magnet can be shifted is constructed so that the smallest contact pressure occurs in a position of the permanent magnet close to the front axle of the car, while the highest contact pressure can be achieved by shifting the position close to the drive motor.
In order to immobilize the adhesion plate in the retaining means, the retaining means is provided with a front holding nose, which can engage the adhesion plate from behind. Simultaneously, the holding nose can limit the displacement distance of the permanent magnet and prevent removal thereof from the retaining means.
The permanent magnet is adjustable along the inclined plane by manual action from the underside of the chassis. Thus, further auxiliary shifting means are not needed.
In order to offer the user the capability of adjusting specific positions of the permanent magnet, the guide rails can contain one or more inwardly directed projections, or the adhesion plate can be provided with transversely directed raised structures, which represent a certain resistance or stop in a particular position during shifting of the permanent magnet.
The permanent magnet is constructed as a one-piece rectangular plate. In an improved embodiment, however, the permanent magnet can also be of two-piece structure, making it possible to spread the contact pressure of the permanent-magnet parts on the roadbed over a larger surface and to achieve even finer adjustment of the contact pressure by pushing the parts of the magnet away from one another.